Rice grain yield is drastically reduced under low light especially in kharif (wet) season due to cloudy weather during most part of crop growth. Therefore, 50–60% of yield penalty was observed. To overcome this problem, identification of low light tolerant rice genotypes with a high buffering capacity trait such as photosynthetic rate has to be developed. Sedoheptulose-1,7 bisphosphatase, a light-regulated enzyme, plays pivotal role in the Calvin cycle by regenerating the substrate (RuBP) for RuBisCo and therefore, indirectly regulates the influx of CO₂ for this crucial process. We found a potential role of SBPase expression and activity in low light tolerant and susceptible rice genotypes by analyzing its influence on net photosynthetic rate and biomass. We observed a significant relationship of yield with photosynthesis, SBPase expression and activity especially under low light conditions. Two tolerant and two susceptible rice genotypes were used for the present study. Tolerant genotypes exhibited significant but least reduction compared to susceptible genotypes in the expression and activity of SBPase, which was also manifested in its photosynthetic rate and finally in the grain yield under low light. However, susceptible genotypes showed significant reduction in SBPase activity along with photosynthesis and grain yield suggesting that tracking the expression and activity of SBPase could form a simple and reliable method to identify the low light tolerant rice cultivars. The data were analyzed using the Indostat 7.5, Tukey–Kramer method through Microsoft Excel 2019 and PAST4.0 software. The significant association of SBPase activity with the grain yield, net assimilation rate, electron transfer rate, biomass and grain weight were observed under low light stress. These traits should be considered while selecting and breeding for low light tolerant cultivars. Thus, SBPase plays a major role in the low light tolerance mechanism in rice.

由于在作物生长的大部分时间里都是多云天气，在弱光下尤其是在kharif（潮湿）季节，稻米产量急剧下降。因此，观察到了 50-60% 的产量损失。为了克服这个问题，必须开发具有高缓冲能力性状（例如光合速率）的耐弱光水稻基因型的鉴定。Sedoheptulose-1,7 双磷酸酶是一种光调节酶，通过再生 RuBisCo 的底物 (RuBP) 在卡尔文循环中发挥关键作用，因此间接调节 CO ₂的流入对于这个关键过程。我们通过分析 SBPase 对净光合速率和生物量的影响，发现了 SBPase 表达和活性在耐弱光和易感水稻基因型中的潜在作用。我们观察到产量与光合作用、SBPase 表达和活性的显着关系，尤其是在低光照条件下。本研究使用了两种耐受性和两种易感性水稻基因型。与敏感基因型相比，耐受基因型在 SBPase 的表达和活性方面表现出显着但最小的降低，这也体现在其光合速率和最后在弱光下的谷物产量上。然而，易感基因型的 SBPase 活性显着降低，光合作用和谷物产量显着降低，表明跟踪 SBPase 的表达和活性可以形成一种简单可靠的方法来鉴定耐弱光水稻品种。数据使用 Indostat 7.5、Tukey-Kramer 方法通过 Microsoft Excel 2019 和 PAST4.0 软件进行分析。在低光胁迫下观察到 SBPase 活性与籽粒产量、净同化率、电子转移率、生物量和籽粒重显着相关。在选择和育种耐弱光品种时应考虑这些性状。因此，SBPase 在水稻耐弱光机制中起主要作用。数据使用 Indostat 7.5、Tukey-Kramer 方法通过 Microsoft Excel 2019 和 PAST4.0 软件进行分析。在低光胁迫下观察到 SBPase 活性与籽粒产量、净同化率、电子转移率、生物量和籽粒重显着相关。在选择和育种耐弱光品种时应考虑这些性状。因此，SBPase 在水稻耐弱光机制中起主要作用。数据使用 Indostat 7.5、Tukey-Kramer 方法通过 Microsoft Excel 2019 和 PAST4.0 软件进行分析。在低光胁迫下观察到 SBPase 活性与籽粒产量、净同化率、电子转移率、生物量和籽粒重显着相关。在选择和育种耐弱光品种时应考虑这些性状。因此，SBPase 在水稻耐弱光机制中起主要作用。